초록 ▼

A folded cascode amplifier with rail-to-rail common-mode range utilizes a fully differential input with two sets of input common source amplifier devices to allow rail-to-rail common-mode range. The first set of devices utilizes N-channel transistors (28) and (32) to provide operation in one directi

A folded cascode amplifier with rail-to-rail common-mode range utilizes a fully differential input with two sets of input common source amplifier devices to allow rail-to-rail common-mode range. The first set of devices utilizes N-channel transistors (28) and (32) to provide operation in one direction and P-channel transistors (38) and (42) to allow operation in the other direction. Two common gate amplifier output legs are provided for generating a differential voltage between an output node (50) and an output node (48) in a cascode configuration. A feedback circuit is provided for maintaining node (50) at analog ground over the full common-mode range of the input voltage. The feedback circuit utilizes a current source with transistors (88) and (90) and a differentially configured set of transistors (80) and (82) to control a feedback transistor (86). The feedback transistor (86) controls the current in both of the output legs to maintain the node (50) at analog ground by receiving at one of the differential inputs the voltage on the node (50) and comparing it with analog ground on the other differential input.

대표청구항 ▼

A folded cascode differential amplifier with rail-to-rail common-node range, comprising: a positive supply rail; a negative supply rail; first common source circuitry for converting a differential input voltage to a first differential current and operable to said positive rail; second common source

A folded cascode differential amplifier with rail-to-rail common-node range, comprising: a positive supply rail; a negative supply rail; first common source circuitry for converting a differential input voltage to a first differential current and operable to said positive rail; second common source circuitry for converting said input voltage to a second differential current and operable with a common-node range to said negative rail; a plurality of first push-pull cascade devices for receiving on an input one side of each of said first and second differential currents for conversion to a voltage on a first output node; a plurality of second push-pull cascode devices for receiving on an input one side of each of said first and second differential currents for conversion to a voltage on a second output node; a first current variable load for varying the current through said first ascode devices to vary the voltage on said first output node; a second current variable load for varying the current through said second cascode devices to vary the voltage on said second output node; and a negative-feedback auxiliary amplifier coupled to said cascode devices and said current variable loads, said auxiliary amplifier operable to maintain said cascode devices in linear operation while permitting variations in load current resulting from rail-to-rail common mode operation.